Marine Technologies, LLC

Bridge Mate™ DP Concept

Design Reduces Risk of Human Error

A large number of DP incidents are related to human error. In an effort to reduce this factor, Marine Technologies has emphasized user-friendly features throughout the design of the Bridge Mate dynamic positioning products, including:

Printed, backlit text on operator panels to provide visual distinction between different buttons

Buttons are separated into different groups based on their functions

Buttons have different shapes based on their function

The placement of buttons on the monitor panel are linked to the graphic user interface to make the functionality of the button intuitive

The same user-friendly principle has been a criteria for design of the software that provides the graphic user interface. Some features are:

A consistent use of colors to indicate status and error conditions

A logical and intuitive placement of critical information in predefined locations, as well as separating features and functions into user selectable views

Architecture

The Bridge Mate DP concept is based on a distributed architecture that emphasizes both redundancy and segregation philosophies. The robust design is important onboard vessels where a service and system specialist is not at hand 24 hours/day, every day.

In addition to distributed operator stations and DP control computers, the Bridge Mate system has distributed thruster and sensor interface units based on a stand-alone I/O unit specially designed for use on DP vessels.

The distributed architecture reduces the cable installation considerably. Each interface unit can be placed close to the thrusters, the reference systems and the sensors to be interfaced. The design of the interface unit makes the Bridge Mate system well suited for retrofit and upgrading within all equipment classes.

Triple Redundant DP Controller

The three DP control computers in the Bridge Mate DP 2 and DP 3 systems are totally independent from each other, running in parallel. This means that each computer will read the same data from the sensors and run this through the same algorithms, resulting in a vector of output signals from each control computer to each individual thruster's interface unit. Each thruster's interface unit runs its own voting algorithm, comparing the signals received from the three control computers. Based on this, it is able to determine the status of a control computer. If one computer outputs a result different from the others, it will be isolated and discarded from the DP system, and an alarm will be provided to the operator. The faulty computer will then try to correct itself by performing a synchronization with the healthy control computers. This computer will only be accepted by the system if it is successful at this.

Redundancy and Segregation Philosophy

The different modules that make up the DP system can easily be placed in a decentralized manner. This applies to control computers, operator stations/computers, as well as I/O units. This ensures flexibility of installation and improves safety, as there is no centralized unit that will take down the entire system in case of a fire or flood. It is also a great benefit that a small set of standardized modules is used for any type of DP class system. This makes it easy to upgrade from one DP class to another and simplifies service and spare part availability.

Online Capability Plots

Bridge Mate now offers online simulation of vessel position holding capabilities for different environmental settings, such as current, wave or wind, or in the event of the loss of thrusters.

Motion Prediction

Bridge Mate motion prediction enables the DP system to predict how the vessel will move in the event of a system failure, such as the loss of a thruster, where the result is loss of position. The motion prediction algorithm, which is an extension of the existing consequence analysis function, will predict the speed and direction of vessel movement. The DP system is continuously performing real-time simulations to estimate how the environmental forces are affecting the vessel and how the vessel would be affected by any system failure. The drift-off projection is graphically indicated as a trace line in a separate view.

Networking

The DP system employs a dual Ethernet for communication between all the modules that comprise the total system. Computers and I/O units are connected to the system via standard network switches using common network standards. The network solution is designed for robustness and reliability. All communication is full-duplex using User Datagram Protocol (UDP) with point-to-point communication instead of broadcast or multicast, preventing packet collision and loss of data.